Older Chrome branches still need the Register() function.

Bug chromium:644329

Change-Id: I6b07aea6e069604f3e5d9e08c97c287df31c0dd6
Reviewed-on: https://swiftshader-review.googlesource.com/7090Tested-by: Nicolas Capens <capn@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
(cherry picked from commit 95db80e4269db8ee31432590defa699d6dd36f6b)
Reviewed-on: https://swiftshader-review.googlesource.com/7091Reviewed-by: Nicolas Capens <capn@google.com>